Lincoln County is one of the five counties created after West Virginia became a state. It is a southwestern county, bounded by Cabell, Putnam, Wayne, Logan, Boone, and Kanawha counties. The Guyandotte River flows through the western part of Lincoln County, while the Mud River flows in the north. Hamlin is the county seat. State Route 10 and State Route 3 are the main roads, although four-lane Corridor G (U.S. 119) touches Lincoln County in the east. Lincoln County has an area of 439 square miles and a 2020 population of 20,463, down slightly from its peak of 23,675 in 1980.

Prehistoric people lived in a village near present West Hamlin. Later Indians, primarily the Shawnee, used present Lincoln County for hunting or as a buffer from the settlers of European descent farther east. Throughout the 1780s and 1790s, fragments of several Indian tribes formed the Mingo tribe and had a strong presence in the area. Indian caves, graves, and mounds are common.

Lincoln County was first populated by European-Americans when the McComas family settled on the Guyandotte near present West Hamlin in 1799. The Hatfields followed about 1800, settling on the river just above the McComases. Other early settlers included William W. Brumfield, at the mouth of Big Ugly Creek about 1801; John Tackett, at Trace Fork in 1801; and David Stephenson, at present Hamlin in 1802. In the next few decades, the region was quietly settled, with much economic activity centering on "the Falls of Guyan," near present West Hamlin. Hamlin, originally Hamline, was a key site on the Mud River. It was established by the Virginia Assembly in 1853 and named for a nearby Methodist church, which took its name from Bishop Leonidas Hamline. Another important town in that vicinity was Griffithsville, established about 1854 and named after an early settler, Alexander Griffith.

In the late 1840s, locks and dams were constructed on the Guyandotte River to carry coal and timber from the valley. Throughout the 1850s, steamboats including the Major Adrian and the R. H. Lindsey made trips up and down the Guyan, as the Guyandotte River is often called. An 1861 flood destroyed the locks and dams, and they were never rebuilt.

The people were about equally divided during the Civil War. There were several military engagements in what is now Lincoln County, but no large battles. Soon after the war, on February 23, 1867, Lincoln County was formed from Boone, Cabell, Kanawha, and Putnam counties, and named for the assassinated president. In 1868, Lincoln's boundaries were drastically changed: Putnam's territory was given back; more land was taken from Boone, Cabell, and Kanawha; and new land was incorporated from Logan and Wayne counties. There was yet another boundary shift in 1869, in which Lincoln took in all of the Harts area and most of the headwaters of Mud River. In the same year, Hamlin was made the permanent county seat.

For the next several decades, timbering was big business in Lincoln County. Men made their living by cutting timber and rafting it downriver to the town of Guyandotte, on the Ohio River. For a brief period, steamboats returned to the Guyan, including the Jennie George, Guyan Valley, Favorite, and others.

The river culture passed away with the construction of the Chesapeake & Ohio Railway along the Guyandotte River in 1902-04, built to develop the coalfields in Logan County. In 1905, the oil and gas business began in Griffithsville, while the timber industry boomed on Big Ugly Creek in the 1910s. Industrialization turned nasty with the burning of the courthouse on November 19, 1909, suspected to have been done to destroy land records and confuse titles.

In the early 20th century, discoveries in oil and gas brought employment and a surge in the county population. From 1900 to 1910, the number of Lincoln Countians jumped from 15,434 to 20,491. After that time, the county's population remained virtually unchanged throughout the remainder of the 20th century. During the Great Depression Depression, conditions in Lincoln County were especially bad. By 1935, 89 percent of all families regularly accepted government relief, although county officials had initially resisted the relief efforts of the Roosevelt administration.

In the 20th century, Lincoln County's education advancements were marked by the construction of four high schools: Duval High School in Griffithsville (1914), Hamlin High School in Hamlin (1922), Guyan Valley High School in Pleasant View (1927), and Harts High School in Harts (1954). In later years, concerns arose as to the education provided to Lincoln County young people. The 1982 ruling by Judge Arthur Recht of the Ohio County Circuit Court that the state legislature had failed to provide an efficient educational system for all children of the state arose from a court case originating in Lincoln County. The state board of education took control of Lincoln County schools in 2000, arguing that local administrators were doing an unacceptable job. Many Lincoln Countians disagreed. They vigorously resisted the take-over and related attempts to consolidate their schools. Nonetheless, the state board voted in 2003 to replace Lincoln County's four high schools with one consolidated high school. Lincoln County High School opened in 2006.

In 2023, Lincoln County's largest employers were the county school system; Lincoln County Opportunity, which oversees senior centers; Lincoln County Primary Care Center; and the county commission.

Lincoln County is the birthplace of Gen. Charles "Chuck" Yeager, the first man to fly faster than sound. John S. Witcher of Hamlin was a Union general during the Civil War, member of the House of Delegates, secretary of state, congressman, collector of internal revenue, and paymaster for the army. Clark W. May of Griffithsville was speaker of the House of Delegates, state Senate president, and state attorney general, before his premature death in 1908. Lloyd Jackson, of Hamlin, had a long career in the state Senate and served as its president.